All about flooble | fun stuff | Get a free chatterbox | Free JavaScript | Avatars    
perplexus dot info

Home > Numbers
Prime+reversal= prime (Posted on 2014-03-04) Difficulty: 2 of 5
Find the smallest prime which can be represented as sum of a prime and its reversal.

See The Solution Submitted by Ady TZIDON    
No Rating

Comments: ( Back to comment list | You must be logged in to post comments.)
Solution a post mortem d1 solution Comment 4 of 4 |
Clearly, if one wants to solve it at first glance, - one would begin testing numbers of a 2?1 structure by choosing a prime one and then trying 2?1*1?2 -  if it's prime - stop. Solved.
No - continue with 2?7.
Ok: 201 not a prime;  211+112=323 not a prime; 221+122=343 not a prime; 231 not a prime;  241+142=  a prime number, smallest, ANSWER.
 
Conclusion - it always pays to try the "guessing process" at least for a while.

  Posted by Ady TZIDON on 2016-12-10 02:23:54
Please log in:
Login:
Password:
Remember me:
Sign up! | Forgot password


Search:
Search body:
Forums (0)
Newest Problems
Random Problem
FAQ | About This Site
Site Statistics
New Comments (2)
Unsolved Problems
Top Rated Problems
This month's top
Most Commented On

Chatterbox:
Copyright © 2002 - 2017 by Animus Pactum Consulting. All rights reserved. Privacy Information